Stronger than a speeding bullet, but lighter

New tests of nanostructured material could lead to better armor against everything from gunfire to micrometeorites

November 9, 2012

This electron-microscope image of a cross-section of a layered polymer shows the crater left by an impacting glass bead, and the deformation of the previously even, parallel lines of the layered structure as a result of the impact. In this test, the layered material was edge-on to the impact. Comparative tests showed that when the projectile hit head-on, the material was able to resist the impact much more effectively. (Credit: Thomas Lab, Rice University)

While traditional shields have been made of bulky materials such as steel, body armor made of lightweight material such as Kevlar has shown that thickness and weight are not necessary for absorbing the energy of impacts.

Now, a new study by researchers at MIT and Rice University has shown that even lighter materials may be capable of doing the job just as effectively.

The key is to use composites made of two or more materials whose stiffness and flexibility are structured in very specific ways — such as in alternating layers just a few nanometers thick. The research team produced miniature high-speed projectiles and measured the effects they had on the impact-absorbing material.

The results of the research are reported in the journal Nature Communications, in a paper co-authored by former postdoc Jae-Hwang Lee, now a research scientist at Rice; postdoc Markus Retsch; graduate student Jonathan Singer; Edwin Thomas, a former MIT professor who is now at Rice; graduate student David Veysset; former graduate student Gagan Saini; former postdoc Thomas Pezeril, now on the faculty at Université du Maine, in Le Mans, France; and chemistry professor Keith Nelson. The experimental work was conducted at MIT’s Institute for Soldier Nanotechnologies.

The researchers developed a self-assembling polymer with a layer-cake structure: rubbery layers, which provide resilience, alternating with glassy layers, which provide strength. They then developed a method for shooting glass beads at the material at high speed by using a laser pulse to rapidly evaporate a layer of material just below its surface.

Though the beads were tiny — just millionths of a meter in diameter — they were still hundreds of times larger than the layers of the polymer they impacted: big enough to simulate impacts by larger objects, such as bullets, but small enough so the effects of the impacts could be studied in detail using an electron microscope.

Seeing the layers

Structured polymer composites have previously been tested for possible impact-protection applications. But nobody had found a way to study exactly how they work — so there was no way to systematically search for improved combinations of materials.

The new techniques developed by the MIT and Rice researchers could provide such a method. Their work could accelerate progress on materials for applications in body and vehicle armor; shielding to protect satellites from micrometeorite impacts; and coatings for jet engine turbine blades to protect from high-speed impacts by sand or ice particles.

The methods the team developed for producing laboratory-scale high-speed impacts, and for measuring the impacts’ effects in a precise way, “can be an extremely useful quantitative tool for the development of protective nanomaterials,” says Jae-Hwang Lee, now a research scientist at Rice, the lead author of the paper, who did much of this research while in MIT’s Department of Materials Science and Engineering. “Our work presents some valuable insights to understand the contribution” of the nanoscale structure to the way such materials absorb an impact, he says.

Because the layered material has such a predictable, ordered structure, the effects of the impacts are easily quantified by observing distortions in cross-section. “If you want to test out how ordered systems will behave,” Singer says, “this is the perfect structure for testing.”

comments 22

Stronger than a speeding bullet? Well, that isn’t saying much. A speeding bullet can be knocked off course by wind or rain, lots of different things. Just ask a sniper. Perhaps a better choice of pronouns might be; Stronger than the Incredible Hulk? But then you might have Marvel and their lawyers out to get you. Or, Stronger Than God? Oops! Now you have all of the religious people and their lawyers out for blood. (Infidel! My God is stronger than your God! No he isn’t! Yes he is! ETC.) And even the
atheist are up in arms claiming that there is no God. Maybe stronger than Hercules? I think that any patent rights on him would have expired after a few thousand years.

you could shoot superman in the eye’ball,and would’nt even make him blink…not the sute dude.,,it’s more like matrix power…
If anyone think’s there will be’another’viet’nam…and our body armor will,,be somekind’ah”–advantage-,,please,,,stop’n'think….fire’fight’s with a.k’s…are ah’thing,,for”war’lords,,,cartel’s…..NOT,,super’power’s……not any’more…..not way……they got’s bigger toy’sz….

I’m sure you all remember the long and contentious argument we had here a few days ago about politics. It all started with a video of a Chinese professor gloating to his students that America had failed.

Well…have you noticed all the important papers posted here with Chinese co-authors? Look at the name of Jae-Hwang Lee above.

The Beijing regime spends millions of Yuan educating great minds only to have them leave for the west. So who is lacking in vision? Who is doing things the wrong way?

Just look at all these late and great discoveries coming from the minds of ex-pat Chinese. While you are at it, look at all the co-authors with names from India.

…and don’t say I’m off-thread. “The work was supported by the U.S. Army Research Office.” So the U.S. Army will have bullet-proof uniforms before the Red Army. It will make them stop and think twice about causing trouble about all of those islands in the South China Sea that may have oil.

What are you talking about, Mr. X? Some of those islands just might belong to Taiwan, or even Japan or the Philippines or Viet Nam.

And don’t accuse me of pissing gas away. I drive a Toyota Yaris that gets 38 miles per gallon and I only fill up my ten gallon tank once every five weeks. I go farther walking my three German shepherds than I do in my car.

So what is your point Russel? Every research center I have worked in since the 1980′s have all had 30%+ of the researchers from China or India. These countries each have 4 times as many people as the US and therefore they have more smart people.

Yeah Marcos. Wouldn’t you like a suit like that? With all these “Stand your ground” laws that allow any troublemaker to carry a concealed weapon, there will be a big civilian market for bulletproof speedos.

but, imagine all the pricks throwing stuff at you, just because you are immune.. nah…
same thing with growing new limbs, imagine the new level of “practical jokes” involving axes just because you can simply regrow them… “Hey transhumanist, lend me your limb for my starfish science fair project?! Thanks!”